Oakland Mariposa Lily

Calochortus umbellatus grows around San Francisco Bay. It is reported also from Lake County.

Stems usually branching, 8–25 cm, not bearing bulblets. Leaves: basal persistent, 2–4 dm; blade lanceolate, flat; cauline usually present. Inflorescences subum-bellate, 3–12-flowered. Flowers ± erect; perianth open, campanulate; sepals 10–14 mm; petals white to pale pink, usually with purple blotch near gland, widely obovate to cuneate, 12–18 mm, adaxial surface not ciliate, ± glabrous, margins irregularly dentate distally; glands basally convex, covered by broad, ciliate membrane, bordered distally by short hairs; filaments longer than anthers; anthers oblong, apex acute or obtuse. Capsules nodding, 3-winged, 1–2 cm. Seeds dark brown, irregular. 2n = 20.

Calif.

Flowering early spring--early summer.

Openings in chaparral or woods, often on serpentine; 100--700m.

Calochortus umbellatus is a rare wildflower endemic to California and restricted to a very narrow range of occurrence. The taxon is characteristically found in open chaparral or woodlands, most typically on serpentine substrate soils. The occurrence is further limited to the southern portions of the Outer North Coast Ranges and the San Francisco Bay Area. coun ties of chief occurrence are Marin, San Mateo, Santa Clara, Alameda and Contra Costa. The Oakland Mariposa Lily appears on the California Native Plant Society list 4.2 of rare and endangered plants. The distribution is restricted to elevations between 100 to 700 meters.

Calochortus umbellatus is a flowering plant in the lily family found only in California in the United States. The common name for this species is Oakland mariposa lily or Oakland star-tulip.